U.S. Pat. No. 4,727,214 describes a process for converting anhydrous or aqueous ethanol into ethylene by means of a catalyst of the crystalline zeolite type, said catalyst having, on the one hand, channels or pores formed by cycles or rings of oxygen atoms having 8 and/or 10 elements or members, and on the other hand, an atomic Si/Al ratio of less than about 20. In the examples, the atomic ratio Si/Al of the FER used is from 5 to 20, the temperature from 217 to 280° C., and the WHSV of 2.5 h−1.
JP 2009-215244 A published on 24 Sep. 2009 relates to a method to produce ethylene by contacting ethanol on a H-FER catalyst, having an atomic Si/Al between 3 and 20, more specifically between 4 and 10, sodium and potassium contents both of 0.1% wt or less, more specifically of 0.005% wt or less, the temperature ranging from 200 to 300° C., pressure from 10 to 100 bara, and WHSV from 0.1 to 10 h−1. In examples, the appraisal of the ethanol reaction is achieved by method of gas pulse reaction using gas chromatograph. In the examples the temperature is 260° C. or under.
WO 2009-098262 (in a first embodiment) relates to a process for the dehydration of an alcohol having at least 2 carbon atoms to make the corresponding olefin, comprising:    introducing in a reactor a stream (A) comprising at least an alcohol, optionally water, optionally an inert component, contacting said stream with a catalyst in said reactor at conditions effective to dehydrate at least a portion of the alcohol to make an olefin,    recovering from said reactor an olefin containing stream (B),    Wherein    the catalyst is:            a crystalline silicate having a ratio Si/Al of at least about 100, or        a dealuminated crystalline silicate, or        a phosphorus modified zeolite,            the WHSV of the alcohols is at least 2 h−1,    the temperature ranges from 280° C. to 500° C.
WO 2009-098262 (in a second embodiment) relates to a process for the dehydration of an alcohol having at least 2 carbon atoms to make the corresponding olefin, comprising:    introducing in a reactor a stream (A) comprising at least an alcohol, optionally water, optionally an inert component, contacting said stream with a catalyst in said reactor at conditions effective to dehydrate at least a portion of the alcohol to make an olefin,    recovering from said reactor an olefin containing stream (B),    Wherein    the catalyst is a phosphorus modified zeolite,    the temperature ranges from 280° C. to 500° C.
It has now been discovered that the dehydration of at least an alcohol to the corresponding olefin made on:    a crystalline silicate of the group FER, MWW, EUO, MFS, ZSM-48, MTT or TON having Si/Al under 100,    or a dealuminated crystalline silicate of the group FER, MWW, EUO, MFS, ZSM-48, MTT or TON having Si/Al under 100,    or a phosphorus modified crystalline silicate of the group FER, MWW, EUO, MFS, ZSM-48, MTT or TON having Si/Al under 100,    has many advantages. Said dehydration is made with a WHSV of at least 4 h−1 or at a temperature from 320 to 600° C.
By way of example, in the dehydration of ethanol on a ferrierite having a Si/Al ratio from 10 to 90 and with a WHSV of at least 4 h−1 to make ethylene, the ethanol conversion is at least 98% and often 99%, advantageously the ethylene yield is at least 97%, the ethylene selectivity is at least 96% and often 97% and the ethylene purity is at least 99% and often 99.8%.    The ethanol conversion is the ratio (ethanol introduced in the reactor−ethanol leaving the reactor)/(ethanol introduced in the reactor).    The ethylene yield is the ratio, on carbon basis, (ethylene leaving the reactor)/(ethanol introduced in the reactor).    The ethylene selectivity is the ratio, on carbon basis, (ethylene leaving the reactor)/(ethanol converted in the reactor).
The ethylene purity is the ratio, on carbon basis, (ethylene leaving the reactor)/(ethylene+ethane leaving the reactor). It means the ethylene purity is the percentage of ethylene, on a carbon basis, present in the C2 cut, containing close-boiling compounds, recovered in the stream leaving the reactor. The C2 cut doesn't comprise the unconverted ethanol and acetaldehyde if any. The same definitions apply mutatis mutandis to the alcohol and the olefin.